Re: [Qemu-devel] [PATCH 3/9] chardev: use a child source for qio input source

[KONRAD Frederic]

Le 4/4/19 à 5:44 PM, Marc-André Lureau a écrit :
> Hi
>
> On Thu, Apr 4, 2019 at 5:18 PM KONRAD Frederic
> <address@hidden> wrote:
> > Hi guys,
> >
> > We have some random delays with gdbstub since this commit under Windows.
> > Basically while debugging the next command can sometimes take more than 5
> > seconds while it usually tooks 30ms before. It is not target dependent I see
> > that happening with sparc, ppc, riscv, etc.. but only on Windows host.
> >
> > Does that ring a bell?
>
> No, is this with a socket chardev or other kind?

It's connecting through the TCP socket. '-s -S' option.

> Could you check the chardev behaviour with the HMP monitor for ex:
> qemu -chardev socket,id=foo,server,host=localhost,port=9999 -monitor chardev:foo
>
> Is this also taking a few seconds to reply?
>
> Have you checked running tests/test-char on windows? Is this also
> taking long (>2sec)?

I'll try to test that.

Thanks!
Fred

> > Cheers,
> > Fred
> >
> > Le 8/28/18 à 12:23 AM, Marc-André Lureau a écrit :
> > > GLib child source were added with version 2.28. We can use them now
> > > that we bumped our requirement to 2.40.
> > >
> > > Signed-off-by: Marc-André Lureau <address@hidden>
> > > ---
> > >    chardev/char-io.c | 48 +++++------------------------------------------
> > >    1 file changed, 5 insertions(+), 43 deletions(-)
> > >
> > > diff --git a/chardev/char-io.c b/chardev/char-io.c
> > > index f81052481a..8ced184160 100644
> > > --- a/chardev/char-io.c
> > > +++ b/chardev/char-io.c
> > > @@ -33,7 +33,6 @@ typedef struct IOWatchPoll {
> > >        IOCanReadHandler *fd_can_read;
> > >        GSourceFunc fd_read;
> > >        void *opaque;
> > > -    GMainContext *context;
> > >    } IOWatchPoll;
> > >
> > >    static IOWatchPoll *io_watch_poll_from_source(GSource *source)
> > > @@ -55,47 +54,24 @@ static gboolean io_watch_poll_prepare(GSource *source,
> > >            iwp->src = qio_channel_create_watch(
> > >                iwp->ioc, G_IO_IN | G_IO_ERR | G_IO_HUP | G_IO_NVAL);
> > >            g_source_set_callback(iwp->src, iwp->fd_read, iwp->opaque, NULL);
> > > -        g_source_attach(iwp->src, iwp->context);
> > > -    } else {
> > > -        g_source_destroy(iwp->src);
> > > +        g_source_add_child_source(source, iwp->src);
> > >            g_source_unref(iwp->src);
> > > +    } else {
> > > +        g_source_remove_child_source(source, iwp->src);
> > >            iwp->src = NULL;
> > >        }
> > >        return FALSE;
> > >    }
> > >
> > > -static gboolean io_watch_poll_check(GSource *source)
> > > -{
> > > -    return FALSE;
> > > -}
> > > -
> > >    static gboolean io_watch_poll_dispatch(GSource *source, GSourceFunc callback,
> > >                                           gpointer user_data)
> > >    {
> > > -    abort();
> > > -}
> > > -
> > > -static void io_watch_poll_finalize(GSource *source)
> > > -{
> > > -    /* Due to a glib bug, removing the last reference to a source
> > > -     * inside a finalize callback causes recursive locking (and a
> > > -     * deadlock).  This is not a problem inside other callbacks,
> > > -     * including dispatch callbacks, so we call io_remove_watch_poll
> > > -     * to remove this source.  At this point, iwp->src must
> > > -     * be NULL, or we would leak it.
> > > -     *
> > > -     * This would be solved much more elegantly by child sources,
> > > -     * but we support older glib versions that do not have them.
> > > -     */
> > > -    IOWatchPoll *iwp = io_watch_poll_from_source(source);
> > > -    assert(iwp->src == NULL);
> > > +    return G_SOURCE_CONTINUE;
> > >    }
> > >
> > >    static GSourceFuncs io_watch_poll_funcs = {
> > >        .prepare = io_watch_poll_prepare,
> > > -    .check = io_watch_poll_check,
> > >        .dispatch = io_watch_poll_dispatch,
> > > -    .finalize = io_watch_poll_finalize,
> > >    };
> > >
> > >    GSource *io_add_watch_poll(Chardev *chr,
> > > @@ -115,7 +91,6 @@ GSource *io_add_watch_poll(Chardev *chr,
> > >        iwp->ioc = ioc;
> > >        iwp->fd_read = (GSourceFunc) fd_read;
> > >        iwp->src = NULL;
> > > -    iwp->context = context;
> > >
> > >        name = g_strdup_printf("chardev-iowatch-%s", chr->label);
> > >        g_source_set_name((GSource *)iwp, name);
> > > @@ -126,23 +101,10 @@ GSource *io_add_watch_poll(Chardev *chr,
> > >        return (GSource *)iwp;
> > >    }
> > >
> > > -static void io_remove_watch_poll(GSource *source)
> > > -{
> > > -    IOWatchPoll *iwp;
> > > -
> > > -    iwp = io_watch_poll_from_source(source);
> > > -    if (iwp->src) {
> > > -        g_source_destroy(iwp->src);
> > > -        g_source_unref(iwp->src);
> > > -        iwp->src = NULL;
> > > -    }
> > > -    g_source_destroy(&iwp->parent);
> > > -}
> > > -
> > >    void remove_fd_in_watch(Chardev *chr)
> > >    {
> > >        if (chr->gsource) {
> > > -        io_remove_watch_poll(chr->gsource);
> > > +        g_source_destroy(chr->gsource);
> > >            chr->gsource = NULL;
> > >        }
> > >    }